Helmholtz+Heat Eqn

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selim
Posts: 14
Joined: 02 Sep 2009, 14:17

Helmholtz+Heat Eqn

Post by selim »

Hi,

I wonder if I could couple the Helmholtz equation with the Convective heat transfer equation.

I have a domain , where only a very small portion of it (a heated section) has a temperature of 1000 K. Free stream temperature is 300K. I am using air as the fluid.

I dont know what type of difficulties I will have in the Elmer solver.

Why in the Elmer front or Elmer GUI, the wave equation is not available?

Any suggestions?

Thanks a lot.
Selim
raback
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Re: Helmholtz+Heat Eqn

Post by raback »

Hi Selim
selim wrote:I wonder if I could couple the Helmholtz equation with the Convective heat transfer equation.
You can introduce some coupling. For example, the sound speed and convection velocity of the Helmholtz equation may be given. There are some underlaying assumptions and to honor them I think that these should not change drastically within one wave-length. The coupling with steady-state solution would be most natural. Then the two models would use different aspects of the same equation to model different timescales: Navier-Stokes & Heat equation for long timescales and Helmholtz for short timescales. If you do not have this kind of scale separation I would not be too optimistic in the coupling. Still this kind of coupling has not been tested so you may need to do some pioneering work.
selim wrote:Why in the Elmer front or Elmer GUI, the wave equation is not available?
Only the most frequently used equations have been implemented in ElmerGUI. The menu structures are defined by xml files (look ElmerGUI manual for details). Some definitions are loaded by default, a few may be appended from directory $ELMER_HOME/bin/edf-extra, but many have still not yet been implemented at all. This is not a major undertaking as we are talking about a few hours for each new solver. Hopefully there will be some more definitions in the near future. The xml files link the keywords in the Models Manual rather directly into menu structures so creating the xml files is not beyond the scope of an advanced user.

BR, Peter
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